1. Field of the Invention
The present invention relates to a mobile radio communication system and a base station, and a mobile radio communication method used therefor, and in particular, to a packet communication method such as an HSDPA (High-Speed Downlink Packet Access) service in the mobile radio communication system.
2. Description of the Related Art
Conventionally, in the HSDPA service, as shown in FIG. 13, DPCHs (Dedicated Physical Channels: individual channels) [DL (Downlink)/UL (Uplink)] are set between a mobile station 102 and a base station 101. In FIG. 13, a base station controller [e.g., RNC (Radio Network Controller)] 103 is connected to the base station 101.
As shown in FIG. 14, the mobile station 102 always receives an HS-SCCH (High Speed Shared Control Channel) of 4 CHs (Channels) designated by the base station 101, detects information on a mobile station ID (Identifier) included in the HS-SCCH, and judges whether the mobile station ID coincides with a mobile station ID of the mobile station 102 itself.
In the case in which the mobile station ID of the mobile station 102 itself is detected in an HS-SCCH, the mobile station 102 uses control information to be sent on the HS-SCCH to receive an HS-PDSCH (High Speed Physical Downlink Shared Channel) which is sent from the HS-SCCH at a predetermined time delay.
In addition, in the case in which data which should be sent on an individual channel (hereinafter referred to as individual channel data) is generated in user data, control information of an higher layer, or the like, the mobile station 102 and the base station 101 send the data immediately using DPCHs (UL/DL) (see 3GPP TR (Technical Report) 25.858 V5.0.0, March 2002).
The above-described HSDPA is a system for performing a high-speed packet transmission on a down line. In an HSDPA service receivable state, a CPICH (Common Pilot Channel), an HS-PDSCH, an HS-SCCH, and a DPCH (DL) are sent on a down line, and an HS-DPCCH (High Speed Dedicated Physical Control Channel) and a DPCH (UL) are sent on an up line.
The CPICH is a pilot signal which is sent to all mobile stations in a cell managed by the base station 101. The CPICH is sent with predetermined power from the base station 101 and is used for path search, estimation of a transmission line, measurement of a receiving quality of DL, and the like. The HS-PDSCH is a shared channel for packet transmission of user data and is used among a plurality of mobile stations in a time-multiplexed manner.
The HS-SCCH is a shared channel for sending control data necessary for receiving a packet sent on the HS-PDSCH and is used among a plurality of mobile stations in a time-multiplexed manner. Each mobile station always receives one or more HS-SCCHs. If the HS-SCCH(s) is directed to the mobile station itself, the mobile station receives a packet of the HS-PDSCH using control information of the HS-SCCH.
The DPCHs (DL/UL) consist of a DPCCH (Dedicated Physical Control Channel: individual control channel) and a DPDCH (Dedicated Physical Data Channel: individual data channel).
On the DPCCH, a TPC (Transmit Power Control) bit, which is transmission power control information of channels to be a pair, and control information of a physical layer such as TFCI (Transport Format Combination Indication: transmission format information),and the like indicating a structure of the DPDCH are sent. On the DPDCH, user data and individual channel data, which is a signal of a higher layer, are sent.
The HS-DPCCH is an individual channel which sends CQI (Channel Quality Indication: down line quality information) determined from a result of quality measurement of the CPICH and ACK/NACK (Acknowledgement/Negative Acknowledgements) which is acknowledgement information of a received packet.
In the packet communication method, mobile stations are classified into groups, the number of which is peculiar to each cell, from an MSI peculiar to each mobile station. Transmission and reception of data such as the control information or the like are performed between the mobile stations and the base station using group IDs of the groups (e.g., see “Digital System Automobile Telephone system, First Section, 4-1-10-3, Designation of Channel Structure” ARIB (Association of Radio Industries and Businesses) RCR STD-27 (revised in May 2002)).
In the conventional packet communication method, since an ID allocated to a mobile station is peculiar to a terminal, group ID (GID) resources cannot be utilized effectively depending upon a connection state.